Nortel Networks Mediant TP-1610 SIP - Manual (Page 173)

Mediant 2000 SIP User’s Manual 11. SNMP-Based Management
Version 4.4 173 July 2005
11.2 Carrier Grade Alarm System
The basic alarm system has been extended to a carrier-grade alarm system. A carrier-grade
alarm system provides a reliable alarm reporting mechanism that takes into account EMS
outages, network outages, and transport mechanism such as SNMP over UDP.
A carrier-grade alarm system is characterized by the following:
• The device has a mechanism that allows a manager to determine which alarms are currently
active in the device. That is, the device maintains an active alarm table.
• The device has a mechanism to allow a manager to detect lost alarm raise and clear
notifications [sequence number in trap, current sequence number MIB object].
• The device has a mechanism to allow a manager to recover lost alarm raise and clear
notifications [maintains a log history].
• The device sends a cold start trap to indicate that it is starting. This allows the EMS to
synchronize its view of the device's active alarms.
The SNMP alarm traps are sent as in previous releases. This system provides the mechanism for
viewing of history and current active alarm information.
11.2.1 Active Alarm Table
The device maintains an active alarm table to allow a manager to determine which alarms are
currently active in the device. Two views of the active alarm table are supported by the agent:
• acActiveAlarmTable in the enterprise acAlarm
• alarmActiveTable and alarmActiveVariableTable in the IETF standard ALARM-MIB (rooted in
the AC tree)
The acActiveAlarmTable is a simple, one-row per alarm table that is easy to view with a MIB
browser.
The ALARM-MIB is currently a draft standard and therefore has no OID assigned to it. In the
current software release, the MIB is rooted in the experimental MIB subtree. In a future release,
after the MIB has been ratified and an OID assigned, it is to move to the official OID.
11.2.2 Alarm History
The device maintains a history of alarms that have been raised and traps that have been cleared
to allow a manager to recover any lost, raised or cleared traps. Two views of the alarm history
table are supported by the agent:
• acAlarmHistoryTable in the enterprise acAlarm
• nlmLogTable and nlmLogVariableTable in the standard NOTIFICATION-LOG-MIB
As with the acActiveAlarmTable, the acAlarmHistoryTable is a simple, one-row-per-alarm table
that is easy to view with a MIB browser.
11.3 Cold Start Trap
Mediant 2000 technology supports a cold start trap to indicate that the device is starting. This
allows the manager to synchronize its view of the device's active alarms. Two different traps are
sent at start-up:
• The standard coldStart trap - iso(1).org(3).dod(6).internet(1). snmpV2(6). snmpModules(3).
snmpMIB(1). snmpMIBObjects(1). snmpTraps(5). coldStart(1) - sent at system initialization.
• The enterprise acBoardEvBoardStarted which is generated at the end of system
initialization. This is more of an ‘application-level’ cold start sent after the entire initializing
process is complete and all the modules are ready.